Certain products and byproducts of naturally occurring metabolic processes in cells can be used for a wide spectrum of industries, including the animal feed industry, food industry, cosmetics industry and pharmaceuticals industry. These molecules, which are joinly referred to as “fine chemicals”, also include lipids and fatty acids, amongst which the polyunsaturated fatty acids constitute an example of one class. Polyunsaturated fatty acids (PUFAs) are added, for example, to children's formula to increase its nutritional value. For example, PUFAs have a positive effect on the cholesterol level in the blood of humans and are therefore suitable for protection against heart disease. Fine chemicals and polyunsaturated fatty acids (PUFAs) can be isolated from animal sources, for example fish, or microorganisms. Culturing these microorganisms allows large amounts of one or more of the desired molecules to be produced and isolated.
Microorganisms which are especially suitable for preparing PUFAs are microorganisms such as Thraustochytria or Schizochytriastrains, algae such as Phaeodactylum tricornutum or Crypthecodinium species, Ciliata such as Stylonychia or Colpidium, fungi such as Mortierella, Entomophthora or Mucor. A number of mutant strains of the microorganisms in question which produce a series of desirable compounds, including PUFAs, have been developed by strain selection. The selection of strains with an improved production of a certain molecule is, however, a time-consuming and difficult procedure. Also disadvantageous is the fact that only specific unsaturated fatty acids, or only a specific fatty acid spectrum, can be produced by a defined microorganism.
As an alternative, fine chemicals can suitably be produced on a large scale via the production of plants which have been developed in such a way that they produce the abovementioned PUFAs. Plants which are particularly well suited to this purpose are oil crops which contain large amounts of lipid compounds, such as oilseed rape, canola, linseed, soya, sunflowers, borage and evening primrose. However, other crops which contain oils or lipids and fatty acids are well suited, as mentioned in the detailed description of the present invention. Conventional plant breeding has led to the development of a series of mutant plants which produce a spectrum of desirable lipids and fatty acids, cofactors and enzymes. However, the selection of novel plant varieties with an improved production of a certain molecule is a time-consuming and difficult procedure or even impossible if the compound does not occur naturally in the plant in question, such as in the case of polyunsaturated C20-fatty acids, and C22-fatty acids and those with longer carbon chains.